Letro dose seems high 
The dose would be high if you just started a cycle and wanted to prevent gyno, water reteniton, fat gain, ect......
However, since you already have Gyno, Your only chance to get rid off it using an Anti-E drug is Letro, and at a dose of of at least 2.5 and a minimum of 30 days.
Is it possible to get rid off a little gyno with a smaller dose, or length of time???....Perhaps....by why spend money, unless the odds are in your favor!!!